US8317689B1 - Miniature endoscope system - Google Patents

Abstract

The present invention relates to a small diameter endoscope in which a handle is removably attached to a probe. The probe includes a fiber optic illumination channel that is concentric about an imaging channel. The handle includes an imaging device that detects light from the imaging channel and a sterile barrier that can be extended over the handle for use. Relay optics couples the small diameter imaging channel to the imaging device in the handle. The probe has a mounting hub that connects the probe to the handle and also serves to optically couple the fiber optic illumination channel to a light source.

Description

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Nos. 60/212,935 filed Jun. 20, 2000, 60/187,305 filed Mar. 6, 2000, 60/156,478 filed Sep. 28, 1999 and 60/153,568 filed Sep. 13, 1999 and is a Continuation-in-Part (CIP) of 09/518,954, filed Mar. 6, 2000, the teachings of which are incorporated herein by reference in their entirety. This application also relates to U.S. application Ser. No. 09/520,648 filed Mar. 6, 2000, and U.S. application Ser. No. 09/521,044, filed Mar. 6, 2000, the contents of the above applications are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

Endoscopes are devices which allow visual examination inside a hollow cavity. In the field of medicine, the use of endoscopes permits inspection of organs for the purpose of diagnosis, viewing of a surgical site, sampling tissue, or facilitating the safe manipulation of other surgical instruments. Laparoscopes are used particularly for examining organs in the abdominal area. Laparoscopes typically include a light pipe for illuminating the region to be viewed, at least one lens assembly for focusing and relaying the image of the illuminated object, and a housing for the entire assembly which is structured to minimize tissue damage during the surgical procedure. The light pipe can include a fiber optic element for illuminating the site. The laparoscope housing includes a distal section that can be inserted within a body cavity and a proximal section which can include a handle that a user grips to position the distal end near the surgical site.

Existing laparoscopes can include an imaging device such as a charge coupled device (CCD). This device can capture an image of an object being viewed and convey it to a display device, such as monitor. There is a continuing need to improve on the operational features and manufacturability of endoscope systems that improve imaging capability and reduce the risk to the patient.

SUMMARY OF THE INVENTION

The present invention relates to a small diameter imaging probe or endoscope having improved resolution and field of view. The distal end of the probe, that is inserted into the tissue under examination, is preferably less than 2 mm in diameter to reduce trauma at the point of insertion and thereby provide access to sites that are otherwise unavailable for endoscopic examination.

In a preferred embodiment, the endoscope has an optical waveguide or elongated rod, which can be made of a transparent material such as a high refractive index glass, an illumination channel, an optical system and an imaging sensor. The outer diameter of the elongated rod is preferably in the range of 0.6-1.6 mm. The imaging device is optically coupled to the rod using one or more lenses.

The waveguide can be used to conduct light from a distal end to a proximal end of the device. The rod can have an outer surface which is coated with an absorbing material or light absorbing layer to inhibit internal reflection and scattering of light. One or more lenses at the distal end of the rod can provide enhanced coupling of light into the distal aperture of the rod.

The illumination channel can surround the rod and transmits light from a light source to an object being examined. The illumination channel is formed with or on the outer surface of the light absorbing layer. A dispersive element can be placed at the distal end of the illumination channel to enhance illumination of the region of interest.

The imaging device can be a charge coupled device (CCD), a CMOS imaging device or other solid state imaging sensor having a two dimensional array of pixel elements. The sensor can capture an image as an object being viewed and transmit it to a computer for storage, processing and/or a display.

In another preferred embodiment, the endoscope has an optical system which includes distal optics and an image relay or tube. The tube can have an inner channel such as a hollow cylinder coated with a light absorbing material to inhibit internal reflection and scattering of light. The endoscope has a duplex configuration which uses a beamsplitter to direct illumination light along the same optical path or air tube used for the transfer of image light from an object being imaged.

The system can use a sheath assembly to provide a sterile barrier over the handle. The barrier can be disposable along with the needle probe.

The light source can be a high power light source. The light can be concentrated by source optics to a polarizer and to a beam splitter before traveling through the tube. The illumination light can be polarized to improve delivery and collection efficiency.

The miniature endoscope system can be used for orthopedic, rheumatologic, general laparoscopic, gynecological or ear, nose and throat procedures, for example. Although many applications require a small diameter to reduce trauma, certain applications can accommodate larger diameters.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic illustration of a preferred embodiment of the endoscope;

FIG. 2 shows a cross-sectional view of the endoscope optical system;

FIG. 3 illustrates a front view of an embodiment of the endoscope optical system;

FIG. 4 shows a schematic illustration of an alternate embodiment of the endoscope shown inFIG. 1;

FIG. 5 illustrates rectangular optics and a rectangular image transmission rod of an endoscope transmitting light to an imaging device;

FIG. 6 illustrates a super-clad structure integrated over a square or rectangular transmission path of an endoscope;

FIG. 7 illustrates a perspective view of a preferred embodiment of the invention;

FIG. 8 illustrates an endoscope having an air tube and a duplex configuration;

FIGS. 9 and 10 show a side view and a perspective view, respectively, of a miniature endoscope;

FIG. 11 illustrates a rod tip of a miniature endoscope;

FIG. 12 shows a cross-sectional view of a miniature endoscope;

FIG. 13 shows a detailed view of the light transfer and imaging system of the endoscope ofFIG. 12;

FIG. 14 illustrates a rod tip of an endoscope mounted within a needle;

FIG. 15 shows a cross-sectional view of an alternate embodiment of an endoscope;

FIG. 16 shows a detailed view of the light transfer and imaging system of the endoscope ofFIG. 15;

FIG. 17 shows a micro endoscope with an external light source;

FIG. 18 illustrates an alternate configuration of a lighting system for a miniature endoscope;

FIG. 19 illustrates a cannula for a miniature endoscope; the cannula having an illumination cannula;

FIG. 20 shows a cannula having a stylet;

FIG. 21 is a perspective view of an alternative embodiment of the miniature endoscope;

FIG. 22 is a top sectional view of the miniature endoscope;

FIG. 23 is a side view, a portion shown in hemline of the miniature endoscope;

FIG. 24 is a rear view of the miniature endoscope;

FIG. 25A is a front view of the base of the miniature endoscope with the needle not attached;

FIG. 25B is an enlarged view of a portion of the connection of the endoscope ofFIG. 25A;

FIG. 26 is a side sectional view of the miniature endoscope;

FIG. 27A is an enlarged sectional view of a portion of the endoscope ofFIG. 26;

FIG. 27B is an enlarged sectional view of the distal end of the endoscope ofFIG. 26;

FIG. 28 is a sectional view of the miniature endoscope taken along the line28-28 ofFIG. 26;

FIG. 29A is an enlarged sectional view of a portion of the endoscope ofFIG. 28;

FIG. 29B is an enlarged sectional view of a portion of the endoscope ofFIG. 28.

DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of the invention is illustrated inFIG. 1 which shows aminiature endoscope10. Theendoscope10 has an image transmission path such as an optical waveguide orelongated rod12 used to view objects to be examined. Theelongated rod12 can be attached to ahandle16. Thehandle16 can house alight source input20 which can connect to alight source18. In a preferred embodiment, thelight source input20 such as a fiber optic cable optically couples thelight source18 to an illumination channel within theendoscope10. Thehandle16 can also house apower input22, used to provide power to theendoscope10. Alternatively, the light source and/or power source can be mounted within the handle.

Thehandle16 can also house animage output24. Theimage output24 provides a connection between an imaging device in the endoscope and an electronic storage and/or display device. In one embodiment, the storage device is acomputer26 which is connected to amonitor28. The imaging device can be a charge coupled device or other pixellated flat panel sensor.

FIG. 2 shows a cross-sectional view of an embodiment of themicroendoscope10. Theelongated rod12 can have a transparent material such as a highindex glass rod30 having a refractive index greater than one, anillumination channel34, an optical element ordistal optics38 andproximal optics42.

Thedistal optics38 can form a virtual image of an object being examined. In a preferred embodiment, thedistal optics38 can be one or more plastic lenses. The high index glass rod orcore30 links thedistal optics38 to relayoptics42 located in a proximal end of theendoscope10. In one embodiment, the distal optics comprise two lenses. The highindex glass core30 can have a refractive index of 1.85 and can reduce the optical path between a virtual image created by thedistal optics38 and therelay optics42. The highindex glass rod30 is preferably free of birefringence to produce an aberration free image at an image sensor44. Stress within theglass core30 is necessary for mechanical strength. In a preferred embodiment, theglass core30 is made of SF57, a pochels glass, which is a glass that can be mechanically stressed without introducing stress birefringence.

The highindex glass core30 can have a tunnel barrier or light absorbing layer orsheath32. The purpose of the tunnel barrier orsheath32 is to absorb unwanted light. One option for a tunnel barrier is described in U.S. Pat. No. 5,423,312, the entirety of which is incorporated herein by reference. This option employs a glass rod having an outer surface that has been roughened and blackened to provide an absorbing barrier. In contrast, the present invention leaves the glass rod intact and provides an external coating having a lower index of refraction to absorb light crossing the rod's external surface. In a preferred embodiment, the tunnel barrier or absorbingsheath32 is EMA or extramural absorption glass (available from Shott Fiber Optics, Southbridge, Mass.). The EMA glass can be extruded during a fiber optics drawing process. The extrusion process leaves the outer surface of the high index glass rod intact. The extruding process instead adds material to the outer surface of the highindex glass rod30 to create a reflective boundary. The extruding process can be performed using a bar in tube drawing process. Similarly, the extruding process can be performed using a differential bar in tube drawing process. In a preferred embodiment, the EMA glass is approximately 5-10 μm thick. The EMA glass can have a refractive index of 1.6, for example.

Theillumination channel34 can be used to provide light from a light source to an object being illuminated. In one embodiment the illumination channel is coupled to glass fiber which is coupled to a light source. In a preferred embodiment, theillumination channel34 can be extruded during a fiber optics drawings process. In another embodiment, this fiber optic drawing process can be performed in a second drawing process. The illumination channel can have a wall thickness of 0.15 mm and can have a refractive index of 1.5 for example. Generally, the illumination channel has a wall thickness in a range of 0.1 mm and 0.2 mm.

The image channel orillumination channel34 can have anouter sheath36. In a preferred embodiment, theouter sheath36 is a polyamide coating. The coating can be between 100 and 150 μm thick. The polyamide coating can be applied in a final fiber optics drawing process. Alternatively, one or more of the layers on the rod can be applied by a coating, dipping or deposition process. The polyamide coating can provide strength to theglass core30. If a glass shatter event were to occur, the polyamide coating can contain the glass from the core30 to prevent injury to the patient. An outer metal or plastic tube can also be used to enclose the distal end of the device.

Theelongated rod12 can also have abinary phase ring40 located at its distal end. Thering40 is positioned on theelongated rod12 so as to abut theillumination channel40. The binary phase ring is coupled to the illumination channel in one embodiment. Thebinary phase ring40 disperses light traveling through theillumination channel34 to provide even illumination of the field of view. In a preferred embodiment, thebinary phase ring40 is made from a plastic material. Thebinary phase ring40 can also have adistal window46. The window can be mounted flush against thedistal optics38.

Theelongated rod12 of theendoscope10 in one embodiment has an outer diameter under 2 mm. In another embodiment, theendoscope10 has an outer diameter of 1.6 mm or less. In a preferred embodiment requiring a small entry site, theendoscope10 has an outer diameter of 1 to 1.2 mm.

FIG. 3 illustrates a front view of an embodiment of anendoscope10. Theendoscope10 can have animage light channel58 and asuper-clad structure68. Theimage light channel58 can include and alight absorbing layer56. Thesuper-clad structure68 can include a first coating orlayer64, a second coating orlayer66 and anillumination channel62. The super cladstructure68 directs light through theendoscope10.

Theimage light channel58 can be made from a transparent material or high index glass core52. In a preferred embodiment, the core52 is made from a material having a constant refractive index to eliminate deviation of light passing through the material. The constant refractive index may be achieved after the stress of a fiber drawing process by using a pockels glass core, for example. Pockels glasses exhibit zero birefringence when placed in compression or tension. The constant refractive index may also be achieved by annealing theimage light channel58 after the fiber drawing process. The core52 can also have afirst diameter54. In a preferred embodiment, thefirst diameter54 is 1.20 mm.

Thelight absorbing layer56 of theimage light channel58, in a preferred embodiment, is a light absorbing glass. Thelight absorbing layer56 can have a higher index of refraction than the core52 and can be made from the same material as the core52. Light absorbing colorants can be added to the light absorbing glass material to raise its index of refraction and increase its light absorption. In a preferred embodiment, the index of refraction of thelight absorbing layer56 is slightly higher than the index of refraction of the core52. Thelight absorbing layer56 can be applied to the core52 using a fiber drawing process, for example.

The high index glass core52 and light absorbinglayer56 can be formed from various types of glass materials. In one embodiment, theimage light channel58 can be formed from an F2 glass core and a BG-4 glass light absorbing layer. The F2 glass core can have a refractive index of 1.620. The BG-4 glass light absorbing layer can have a refractive index of approximately 1.65. In another embodiment, theimage light channel58 can be formed from an F7 glass core and a BG-2 glass light absorbing layer. The F7 glass core can have a refractive index of 1.625. The BG-2 glass light absorbing layer can have a refractive index of approximately 1.66.

Thelight absorbing layer56 can have a thickness as low as 5 μm. Preferably, the thickness of thelight absorbing layer56 is no greater than 10 μm. Theimage light channel58, formed of the core52 and thelight absorbing layer56, can have asecond diameter60. In one embodiment, thesecond diameter60 is 1.24 mm.

Theillumination channel62 has thefirst coating64 and thesecond coating66 to form asuper-clad structure68. Thefirst coating64 is located on an inner surface of thechannel62. Thesecond coating66 is located on an outer surface of thechannel62. Theillumination channel62 can be made from a high index of refraction material. In one embodiment, theillumination channel62 can be made from LG1 glass which can have a refractive index of approximately 1.82. Both thefirst coating64 and thesecond coating66 can be made from a low index of refraction material. In one embodiment, thecoatings64,66 can be made from EG1 glass which can have a refractive index of approximately 1.50. In another embodiment, the coatings can be made from EG9 glass which can have a refractive index of approximately 1.56. The low index material can provide for illumination containment of theillumination channel62. Theillumination channel62 can have a thickness of 30 μm. The first64 and second66 coating layers can each have a thickness as low as 5 μm respectively. Preferably, the thickness of each of the first64 and second66 coating layers is 10 μm.

Thesuper-clad structure68 can be made by different processes such as a triple-glass, a tube-extrusion process, a dip coating process or chemical deposition combined with fiber drawing processes, for example.

In one embodiment of a process to fabricate asuper-clad structure68, theimage light channel58 can be exposed to a triple-glass tube-extrusion process, which can form thesuper-clad structure68. A bar-in-tube fiber draw can then be used to fuse thesuper-clad structure68 around theimage light channel58.

In another embodiment of forming asuper-clad structure68, animage light channel58 can be dipped in a low index, high temperature polymer to form afirst coating64. A high index plastic can then be extruded over the polymer cladimage light channel58, to form anillumination channel62. The entire structure can then be dipped in a low index polymer to form thesecond coating66.

In another embodiment of a process of fabricating asuper-clad structure68, a metal layer can be chemically deposited onto both sides of anillumination channel62 to form asuper-clad structure68. In a preferred embodiment, the metal is aluminum. Thesuper-clad structure68 can then be fused to animage light channel58 using a bar-in-tube fiber drawing process. Thesuper-clad structure68 and theimage light channel58, the endoscope50 can have athird diameter70. In one embodiment, thethird diameter70 is 1.65 mm.

In an alternate embodiment, the endoscope can have an angled distal tip in the shape of a needle shown inFIG. 4. This tip provides for ease of insertion at the site to be examined.

The endoscope can also have square or rectangularly shaped distal optics which can form a virtual image of an object being examined. The endoscope can also have an image transmission path or image channel, such as an elongated rod, which can have a square or rectangularly shaped cross section. Similarly, the endoscope can have square or rectangularly shaped relay optics. By using rectangular optics or a rectangular transmission path, a more efficient transfer of light can be made from an object being viewed to an imaging device, which has a square or rectangular imaging area. All light from an object being imaged can be directly transferred to the imaging area, with little to no light wasted during the transfer.

Generally, endoscopes have circular optics which can transmit light rays to a rectangularly shaped imaging device. For endoscopes having optics with circular cross-sectional areas greater than the cross-sectional area of the imaging device, a portion of the light rays traveling in the arcuate areas of the circular optics will not be transmitted to the imaging device. These light rays can be considered as “wasted” since the light rays fail to intersect the imaging device and are, therefore, unused.

FIG. 5 illustrates rectangular distal optics oroptical elements88 for an endoscope which can transmit light rays to an imaging device44. In this embodiment, all light rays from the rectangulardistal optics88 can be transferred to theimaging device84. More light from the object being imaged can therefore be transferred to theimaging device84 with little waste. A rectangularly shapedtransmission path90 can be used to transfer the light from thedistal optics88 to the imaging device44. Rectangularly shaped relay optics86 can also be used to transfer the light from thedistal optics88 to the imaging device44.

When a square or rectangular transmission path is used in a microendoscope, the inner surface of a super-clad layer of the microendoscope can be shaped to conform to the outer surface of the transmission path.FIG. 6 illustrates amicroendoscope94 having a rectangularlight transmission path96 and asuper-clad layer98. Thelight transmission path96 has anouter surface100 which can be coated with a light absorbing layer which conforms to the geometry of theouter surface100. When thesuper-clad layer98 is to be applied to or extruded over thelight transmission path96, aninner surface102 of thesuper-clad layer98 can conform to the geometry of thelight transmission path96, as illustrated. For a squarelight transmission path96, theinner surface102 of thesuper-clad layer98 can be extruded square over thetransmission path96.

FIG. 7 shows a perspective view of a miniature needle endoscope in accordance with the invention. Fiber and electrical cables are connected to the proximal end ofhandle16 orneedle12 for insertion into a patient is attached at a distal end ofhandle16.

A preferred embodiment of the invention can be considered as three subassemblies. A first subassembly shown inFIG. 9 is theouter handle housing120 having adistal rod connector122. A second subassembly is theinner handle140 shown inFIG. 12.Inner handle140 includes proximally located fiber andelectrical connectors142 and144 that are attached to an inner cage assembly146. Thefiber connector142 connects light from an external source to an illumination annulus154 which couples light to anillumination channel308 inneedle240 as shown inFIG. 19. Light collected throughneedle240 is coupled tolenses150 and152 onto an imaging sensor such asCCD148.

FIGS.9 and12-14 illustrate a disposable third assembly having a rod and needle with adistal lens assembly162 that is attached to asterile sleeve assembly160. Thesleeve assembly160 includes asleeve164 that extends over the handle orbase unit202. The distal end ofsleeve164 is secured betweenplastic frames166,170 which can form a mountinghub218.Frame166 has ahole168 that connects to rod andlens assembly162. Frame170 connects to rod connector orinterface connector122.

FIG. 8 illustrates an endoscope, identified generally as130. Theendoscope130 can have anoptical system123 and ahandle124. Theoptical system123 can include atube103 having adistal end112, aproximal end111 anddistal optics117 and can have an outer diameter between 0.6 and 2.0 mm with a preferred outer diameter of about 1.6 mm. Theoptical system123 can be disposable. Thehandle portion124 can includeproximal optics105, animage polarizer106, animage sensor107 and abeam splitter104. Theproximal optics105 can include an achromatic lens. Thebeam splitter104 can be coated with a dielectric coating. The beam splitter coating can be designed to provide maximum reflection of “s polarized” illumination flux and maximum transmission of “p polarized” image light. The curvature of thedistal optics117 can be chosen to minimize retro-reflections of illumination flux appearing in the image.

Theendoscope130 can have a duplex configuration wherein the duplex configuration integrates illumination optics and uses thebeam splitter104 to direct illumination energy along the same optical path used for image light transfer. “Duplex” refers to the optical components and optical path used by illumination flux and image light.

The basic optical components used for both the image light and illumination flux in theendoscope130 are shown inFIG. 8. As part of the imaging component of theendoscope130, anobject plane101 can be located from 2 to 20 mm in front of adistal tip126 of theendoscope130. Thedistal optics117 form a demagnifiedvirtual image114, located just outside thedistal tip126. A narrow beam of image light from thevirtual image114 can pass through thetube103, through a dielectric coatedbeam splitter104, towardproximal optics105, and eventually to animage sensor107, where a real image is formed.Image polarizer106 can be a linear polarizer that is “crossed” with anillumination polarizer108 to block retro-reflected illumination flux originating from surfaces of the distal optics.

Thetube103 can be a stainless steel extrusion having a rough inner surface which can be coated with a light absorbing coating, such as spray paint. For example, Krylon #1602, a dull black paint can be used. Thetube103 can have an inner diameter of 1.5 mm with the light absorbing inner wall to reduce or eliminate veiling or scattered light at theimage sensor107. Thetube103 can be filled with air or some other inert gas, or can be evacuated.

The image channel orimage relay103 functions to minimize or absorb unwanted light and hard to image light to prevent veiling glare. Theimage relay103 provides high resolution of the optical image,114 at the plane of the imaging device, removes intermediate image planes and reduces the tolerances needed for optical alignment and optical fabrication. Theimage relay103 has an inner tunnel wall that can absorb light diverging from theoptics117. The rough wall surface can disperse up to about 95% or more of unwanted light. Theimage relay103 can have a length to diameter (L to D) ratio of between 40:1 and 60:1. The length of the tunnel can be approximately 60 mm. The length of theimage relay103 affects proper illumination of an imaging device, helps control depth of field of view, increases F number for adequate depth of field of view. Theimage relay103 can also be disposable.

The optical element ordistal optics117 on thetube103 can be a polymer lens or an epoxy lens. The distal optics can have a diameter of 1.5 mm. Thedistal optics117 can be a single distal lens to reduce retro-reflections. Thedistal optics117 can be formed from an epoxy using an injection method. In this method a mandrel can first be placed within thetube103 from thedistal end112 to theproximal end111. Epoxy can then be ejected from the needle within 1 mm of thedistal end112 of thetube103. The epoxy can then be exposed to ultraviolet (UV) light to cure the epoxy. Thedistal optics117 can be formed as a concave/negative lens because of the capillary action caused by theair tube103 after ejection of the epoxy from the needle. The distal117 and proximal105 optics can allow control of the size of an image.

The area surrounding theproximal end111 of the tube can be carefully sculpted and blackened to reduce retro-reflected energy at theimage sensor107 originating from the illumination flux overfill of theair tube103. Theproximal optics105 are “looking at” this overfill area and theimage polarizer106 can transmit scattered, unpolarized light to theimage sensor107.

Theendoscope130 can be linked via'beamsplitter104 to anillumination system116. Theillumination system116 can include anillumination source110 such as a COTS lens end Halogen Lamp having a 0.25 inch diameter from Gilway Technical Lamp. The COTS “Lens End” lamp can have high flux output from a small filament. Theillumination source110 can provide high color temperature visible light forobject plane101 illumination.Source optics109 can concentrate illumination flux at theproximal end111 of thetube103 and provide a low divergence beam to maximize transmission of illumination flux through thetube103. Abeam splitter104 can redirect illumination flux along an imagelight axis115.Illumination polarizer108 is a linear polarizer oriented to provide “s polarization” at the beam splitter to maximize reflection of illumination flux from dielectric coatedbeam splitter104, alongaxis115. A light absorbing mechanism orbeam dump113 can remove unused portion of illumination flux from the system to reduce veiling background light that can find its way onto the image sensor.

Illumination optics must be carefully designed to maximize illumination at object plane. The illumination optics create a small spot of light at proximal end of air tube and a collimated beam for maximum transmission through air tube.

Illumination and image polarizers must provide high polarization purity with minimum absorption. For example, dichroic sheet polarizers can be inexpensive, but lossy. Calcite polarizers can be more efficient, but expensive and more difficult to accommodate in a simple optical design.

Unused illumination flux transmitted by the beam splitter must be completely removed from the system because the proximal optics are “looking at” thedump area113. The image polarizer will transmit scattered, unpolarized light to the image sensor.

All retro-reflections can be minimized using well known “optical isolation” configurations, but not totally eliminated. Therefore, electronic image processing may be required to produce an acceptable image. Since the retro-reflection pattern at the image sensor is unique for each scope, this unwanted light distribution can be recorded for each scope, stored in an image buffer, and subtracted from the video image in real time.

Theendoscope130 can be inserted into a body using a cannula. During an insertion procedure, a cannula can first be inserted into a site within a body. Theoptical system123 of theendoscope130 can then be inserted within the cannula which can have an outer diameter of 1.6 mm. Theoptical system123 can pass through the cannula and into the body to provide the user with an image of the site.

The system can be used with a disposable sleeve or sheath to aid in maintaining a sterile environment and reduce the sterilization requirements prior to reuse.

FIGS. 9 and 10 illustrate a miniature endoscope, given generally as200, in both a side and a perspective view respectively. Theendoscope200 can include abase unit202 and asheath assembly160. The base unit can include acable224 which can provide power to an internal light source within thebase unit202. The sheath assembly can include asterile barrier164 and a probe or rod andlens assembly162. The rod andlens assembly162 can be formed of a rod orwaveguide204 and aobject lenses206. The waveguide can be a hollow channel. The probe can have an annular illumination channel around the waveguide. The probe can have a length between 2 cm and 10 cm. Thesterile barrier164 and the rod andlens assembly162 can be attached to a mountinghub218 or second locking element which secures to a first locking element of thebase unit202 of theendoscope200. Thehub218 can include aninterface connection122 or first locking element that allows thesheath assembly160 to attach to thebase unit202. Theinterface connection122 can be a securing mechanism such as a locking mechanism. Thesterile barrier164 can attach to the mountinghub218 by bonding. The bonding can include cementing between thesterile barrier164 and thehub218, for example. The mountinghub218 can include alocking mechanism216 such as a luer lock for example. Thelocking mechanism216 can allow connection between theminiature endoscope200 and a needle such as a 14 gage cannula, for example (manufactured by Popper).

The rod andlens assembly162 can include arod tip226 illustrated inFIG. 11. Therod tip226 can haveobject lenses206. These object lenses can include afirst object lens208 and asecond object lens210. Therod204 of the rod andlens assembly162 can be covered by atube214 or light absorbing boundary. The tube can be a dark coating in order to reduce or eliminate veiling or scattered light within therod204.

Thesterile barrier164 of thesheath assembly160 can cover theentire base unit202. This covering provides a sterility of thebase unit202 during a surgical procedure.

Theminiature endoscope200 can be inserted into a cannula orneedle240 as illustrated inFIGS. 12-16. Preferably theneedle240 has a blunt end. The needle can be a 14 gauge needle. To use theminiature endoscope200 with theneedle26 in a surgical procedure, asheath assembly160 can first be placed on abase unit202. The rod andlens assembly162 of thesheath assembly160 can lock into theinterface connection122 of thebase unit202. A needle orcannula240, having astylet320, such as seen inFIG. 20, slidably mounted within the cannula, can be inserted into a surgical site. In the case where a blunt needle orcannula240 is used, thestylet320 can cut into the tissue of a surgical site and thereby allow theneedle240 to be inserted into the surgical site. Thestylet320 can then be removed from thecannula240. The stylet orobturator320 fills the center portion of the cannula during insertion into a surgical site. The use of the stylet prevents coring of tissue, whereby a cylindrical portion of tissue enters the needle orcannula240 and can clog the needle cavity. By having a stylet within theneedle240, no such tissue can enter thecannula240 and can clog the needle cavity.

Once the stylet has been removed from theneedle240, the user can flush the surgical site with saline. Next, the rod andlens assembly162 of theminiature endoscope200 can be introduced into theneedle240. Therod portion204 can be inserted within theneedle240 so that a user can obtain a view of the surgical site. The needle can include a locking mechanism on its proximal end, such as a luer lock for example. The luer lock can attach to thelocking mechanism216 of the mountinghub218 thereby providing a secure attachment between theendoscope200 and theneedle240.

FIGS. 12,13 and14 illustrate a cross sectional view of theminiature endoscope200. Theendoscope200 can include a lighting system orlight source236 and animaging system238. Thelighting system236 can include alamp242, apolarizer244 and alens expander246. Thelamp242 can be mounted within thebase unit202 by alight source housing270 and can be a high output light source. Thepolarizer244 can polarize light from the light source and direct light towards theexpander246. Thelens expander246 can direct light towards aprism264.

Theimaging system238 of theendoscope200 can include a firstimage path lens150, a secondimage path lens152 and asheet polarizer252. The imaging system can be mounted within ahousing140. Thesheet polarizer252 can help to eliminate back reflections from the rod andlens assembly162. Thepolarizer252 can have a polarization purity of 10⁻³.

FIG. 13 illustrates a light transfer andimaging system262 of theendoscope200 ofFIG. 12. The light transfer andimaging system262 can include abeamsplitter264 which can be mounted within ahousing266 in theendoscope200. Thebeamsplitter264 can be a prism for example. Thebeamsplitter266 can direct light from thelens expander246 into therod204 of the rod andlens assembly162. This light can be directed at an object to be imaged. Thebeamsplitter264 can also receive image light through the rod orchannel204 of an object being imaged and transfer that light to thepolarizer252 of theimaging system238. Thebeamsplitter264 can be mounted within theendoscope200 at a Brewster's angle with such a mounting. Thebeamsplitter264 in this example can form a 33.5° angle with respect to thelong axis272 of the rod. Thebeamsplitter264 can also form a 33.5° angle with respect to the central axis of theimaging system238.

FIG. 12 also illustrates animage sensor148 mounted within thebase unit202 of theendoscope200. Theimage sensor148 can be mounted within animage sensor housing258 within theendoscope200. Theimage sensor148 can be attached to anelectrical cable connector254 whereby thecable connector254 can attach to acable230 to provide image signal data from an object being imaged to an external unit. The external unit can be a television screen, for example. Theimage sensor148 can be a charge coupled device (CCD). The CCD can be a ⅛ inch CCD. By using a ⅛ inch CCD, the user can quadruple the amount of light he receives from an image. When using a ⅛ inch CCD chip, the focal length of theendoscope200 can be between 25 and 30 mm. Preferably the focal length is 27 mm.

FIG. 14 illustrates therod tip260 of theminiature endoscope200 whereby therod tip260 includes thefirst object lens208, thesecond object lens210 and a dark coating ortube214 around arod204. As shown, therod tip260 is mounted within a needle orcannula240. Such insertion of therod tip260 within thecannula240 can be done after thecannula240 is inserted into a surgical site of interest. Once therod tip260 is placed in thecannula240, thecannula240 can lock on to thebase unit202 by means of a locking mechanism.

FIGS. 15 and 16 illustrate an alternate to theimaging system238 illustrated inFIGS. 12,13 and14. Theimaging system238 can include a firstimage path lens150, a secondimage path lens152 and apolarizer280. Thecross polarizer280 can be made from cal cite and can eliminate back reflections created by the rod andlens assembly162. The polarization purity of the cross polarizer can be between 10⁻⁵and 10⁻⁶. Thecross polarizer280 can increase light throughout by 15% to 20%. Thepolarizer280 can include afirst prism282 and asecond prism284. Thepolarizer280 can be attached to thehousing140 of theendoscope200 by apolarizer housing286.

FIG. 16 illustrates the light transfer andimaging system262 ofFIG. 15. Light directed from thelens expander246 can be sent through thebeamsplitter264 and into therod204 to an object being imaged. Light from the object being imaged can be transferred back through therod204 and through theprism264 into thebeamsplitter280. The beamsplitter can transfer the image light to thepolarizer280 which can eliminate back reflections created by theobject lenses206.

FIG. 17 illustrates aminiature endoscope200 where the light source of theendoscope200 is an externallight source290. The external light source can include alamp292 andlight source optics294. Thelamp292 can be a xenon lamp which can be 300 watts, for example. Theoptics294 andlamp292 of the externallight source290 can be coupled to theminiature endoscope200 by asilica cable296. Theendoscope200 can include areducer298 mounted within thebase unit202. Thereducer298 can reduce the cross sectional area of the source by a factor of 2-5 times. Preferably the reducer reduces by a factor of 3.5. When used with a xenon source, thereducer298 can reduce the aperture size of source for efficient coupling into the probe waveguide. The use of areducer298 within theendoscope200 can simplify the optics within thelighting system236.

FIG. 18 shows a configuration of theendoscope200 wherein thelighting system236 is mounted within thebase unit202 parallel to theimaging system238. With such a configuration, thelighting system236 can include amirror302. Themirror302 can be a fold mirror for example. Themirror302 can be mounted within theendoscope200 such that light from alight source242 which travels through apolarizer244 and anexpander246 can reflect from the mirror to travel to theprism264.

FIG. 19 illustrates the cross section of aneedle240 wherein the needle acts a reducer to provide light to an object being imaged. Theneedle240 can include anaperture304. The aperture can be surrounded by afirst cladding layer306, anillumination channel308 and asecond cladding layer310. The first cladding layer can have a firstcladding layer thickness312. Theillumination channel308 can include a channel thickness314 which can be 10 microns. Thesecond cladding layer310 can include asecond cladding thickness316 whereby the thickness can be 3 microns.

FIG. 20 illustrates acannula240 having a stylet. Prior to inserting aneedle240 into a surgical site, a stylet or obturator can be inserted within theneedle240. The stylet can include a cuttingsurface322 and acleaning edge324. When thestylet320 andneedle240 are inserted into a surgical site, tissue can accumulate in an area between thestylet320 and theneedle240. In order to eliminate this material from the area, thestylet320 can include acleaning edge324 whereby the cleaning edge is formed of a less stiff material than is thecutting edge322. When thestylet320 is pulled towards the user after insertion of theneedle240 in the surgical site, the weaker edge or thecleaning edge324 will bend about the needle thereby cleaning or wiping away any tissue debris from the needle area. Such a cleaning function allows proper insertion of the microendoscope within the cannula and proper viewing of a surgical site.

FIG. 21 shows aminiature endoscope400 in side perspective view. Theendoscope400 includes abase unit402 and asheath assembly404. Thebase unit402 includes anelectrical connection406 for the imaging device, such as a CCD and a fiber opticlight source connection408.

Thesheath assembly404 includes asterile barrier410 and a rod andlens assembly412. Thesterile barrier410 and the rod andlens assembly412 are attached to a mountinghub414, which is secured to thebase unit402 of theendoscope400. The mountinghub414 is a light sheath hub with luer lockside port.

Thehub414 can include aninterface connection416 that allows thesheath assembly404 to attach to thebase unit402. Theinterface connection416 can be a securing mechanism such as a locking mechanism. Thesterile barrier410, as seen inFIG. 22, is attached to the mountinghub414 by bonding. The bonding can include cementing between thesterile barrier410 and thehub414, for example.

The mountinghub414 can include alocking mechanism418 such as a luer lock or fitting for example. Thelocking mechanism418 can allow connection between theminiature endoscope400 and a needle such as a 14 gage cannula, for example (manufactured by Popper).

Referring toFIG. 22, a sectional view of theendoscope400 is shown. Thesheath assembly404 with the rod andlens assembly412 andsterile barrier410 is shown. Thesterile barrier410 and the rod andlens assembly412 are attached to the mountinghub414. The mountinghub414 has afiber optic window420 which transmits light from a light source to a light sheath in an obturator. Thewindow420 can be a lens.

Still referring toFIG. 22, the rod andlens assembly412 has a darkenedouter tube422 and a pair ofobject lenses424. The distal end of the rod andlens assembly412 will be discussed in further detail with reference toFIG. 27B.

Referring toFIG. 23, thebase unit402 of theendoscope400 has amain scope body428 with theCCD camera430, a set oflenses432, and a fiberoptic tip mount434 andfiber optic bundle436 which define anopening438 through which an optical image passes from the rod andlens assembly412 towards theCCD camera430. Theopening438 can be covered by a window or a lens. Still referring toFIG. 23, underlying the main scope by428 is afiber optic442 which extends from the fiber opticlight source connection408 tofiber optic bundle436.

FIG. 24 shows the rear portion of thebase unit402 of theendoscope400. Theelectrical connection406 is seen and in addition the fiber opticlight source connection408 is shown.

Referring toFIG. 25A, a front view of thebase unit402 is shown with thesheath assembly404 removed. Thebase unit402 has a plurality offiber optic fibers444 forming anannulus445 surrounding theopening438 as seen inFIG. 25B. Thefiber optic bundle436 is formed of thesefiber optic fibers444 in one embodiment. Alternately, thefiber optic bundle436 has a single fiber optic fiber. Theannulus445 can be a continuous circular pattern. Alternately, the annulus is formed of twosemicircular portions457. Aslot459 can separate thesemicircular portions457. Theslot459 can allow mechanical attachment of thelight sheath422, shown inFIG. 27B to thehub446.

Referring toFIG. 26, a side sectional view of theendoscope400 is shown. Themain scope body428 as indicated above, has theCCD camera430 which is connected through theelectrical connection406 to a monitor, such as illustrated inFIG. 1. TheCCD camera430 captures the image projected through the set oflenses432 that is projected from the high index glass rod of thesheath assembly404. While the sheath assembly is solid, the image that is projected through thelens432 in the main scope body is through theopening438. To light the image, thefiber optics442 directs the light from the fiber opticlight source connection408 to thefibre optic bundle436. Thefiber optic bundle436 can be formed of a plurality of fiber optics or from a single fiber optic.

Referring toFIG. 27A, thefiber optic bundle436 projects its light through thelens432 into thelight sheath448. Thelens432 can be a window, in an alternate embodiment. The connector between thebundle436 and thelens432 is shown inFIG. 29A.

The disposable optictube hub connector446 withlens432 can attach to an obturator or needle having a flushingport450, as shown inFIG. 26. The flushingport450 can include acap452. The flushingport450 allows a user the ability to flush a needle, after insertion into a surgical site, either when the rod andlens assembly412 is located within the needle or has been removed from the needle. A fluid source, such as a syringe filled with saline, for example, can be attached to theport450. When a user flushes the needle with saline while the rod andlens assembly412 is located within the needle, the endoscope can block fluid from flowing from a proximal end of the needle, thereby concentrating flow through a distal end located within a surgical site. Alternately, for a user to flush the needle without therod assembly412 within the needle, thecap452 can be used to cover the proximal end of the needle to direct the flow of the fluid to the distal end of the needle. Such flushing can allow clear viewing of a surgical site.

Referring toFIG. 27B, the distal end of thesheath assembly404 has thelight sheath448 and encircles the disposable opticdark tube422 containing theobject lenses424. Light can be transferred from thefiber optic bundle436 through the light sheath and to an object being imaged.

FIG. 28 is a sectional view taken along the line28-28 ofFIG. 26. The figure shows a sectional view of themain scope body428 cut through and looking up from theoptical opening438. TheCCD430 withconnection406 is shown. Likewise thelens432 through which the image project are shown.

Thefiber optic bundle436, through which light is passed from thefiber optic442, as shown inFIG. 26, encircles a portion of theoptical opening438 and directs light through thelens432 in the disposable optics darktube hub connector446 into the light sheath surrounding the rod andlens assembly412.

FIG. 29A is an enlarged sectional view of the interface of thefiber optic bundle436, the disposable optics darktube hub connector446 and the mountinghub414.

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims (42)

1. A miniature endoscope for orthopedic imaging comprising:

a probe for orthopedic diagnostic imaging, the probe including a fiber optic imaging waveguide that transmits an image, and having a diameter of less than 2 mm and a length between 2 cm and 10 cm, the probe having a mounting hub;

a fiber optic illumination channel within the probe that is concentric about the optical waveguide, the illumination channel being positioned between an inner sheath and an outer sheath;

a handle removeably attached to the mounting hub of the probe with a connector;

a light source that is optically coupled to the fiber optic illumination channel with the mounting hub;

a cannula that receives a distal end of the probe such that the outer sheath slides within the cannula, the cannula having a locking mechanism at a proximal end that attaches to the probe;

a sterile barrier attached to the mounting hub and that can be extended over the handle;

an optical lens coupled to a distal end of the waveguide;

an optical relay mounted in the handle and that is optically coupled to a proximal end of the waveguide; and

an imaging device mounted in the handle at a proximal end of the optical relay that receives an image from the optical waveguide.

2. The miniature endoscope ofclaim 1 wherein the endoscope has an outer diameter of 1.6 mm or less.

3. The miniature endoscope ofclaim 1 wherein the waveguide has an outer diameter between 0.6 and 1.6 mm.

4. The miniature endoscope ofclaim 1 wherein the illumination channel includes a binary phase ring which disperses light from the illumination channel.

5. The miniature endoscope ofclaim 1 wherein the waveguide comprises a glass having a refractive index in the range between 1.6 and 1.9.

6. The miniature endoscope ofclaim 1 wherein the waveguide comprises a glass rod.

7. The miniature endoscope ofclaim 1 wherein the optical waveguide further comprises a light absorbing layer having a thickness between 5 and 10 μm.

8. The miniature endoscope ofclaim 1 wherein the optical waveguide further comprises a light absorbing layer having an extramural absorption glass.

9. The miniature endoscope ofclaim 1 wherein the optical waveguide further comprises a light absorbing layer having a refractive index of 1.6 or less.

10. The miniature endoscope ofclaim 1 wherein the illumination channel has a wall thickness in a range of 0.1 mm and 0.2 mm.

11. The miniature endoscope ofclaim 1 wherein the illumination channel has a refractive index in a range between 1.4 and 1.6.

12. The miniature endoscope ofclaim 1 wherein the outer sheath comprises a metal tube.

13. The miniature endoscope ofclaim 12 wherein the outer sheath comprises a polyamide coating.

14. The miniature endoscope ofclaim 13 wherein the polyamide coating has a thickness between 100 and 150 μm.

15. The miniature endoscope ofclaim 1 wherein the optical relay comprises one or more lenses.

16. The miniature endoscope ofclaim 1 wherein the optical lens comprises a plastic lens.

17. The miniature endoscope ofclaim 1 wherein the imaging device comprises a charge coupled device.

18. The miniature endoscope ofclaim 1 wherein the cannula further comprises a distal needle that penetrates tissue.

19. The miniature endoscope ofclaim 1 further comprising a display connected to the imaging device.

20. The miniature endoscope ofclaim 1 wherein the illumination channel is optically coupled to a light source with a lens in the handle.

21. The miniature endoscope ofclaim 1 further comprising an optical coupler that optically connects the light source to the illumination channel.

22. The miniature endoscope ofclaim 1 wherein the cannula further comprises a fluid delivery port.

23. The miniature endoscope ofclaim 22 wherein the barrier is attached to a rigid waveguide housing that is connected to the handle.

24. The miniature endoscope ofclaim 1 wherein the light source comprises a lamp within the handle that is optically coupled to the illumination channel.

25. The endoscope ofclaim 1 further comprising a tube around the optical waveguide and an outer tube around the fiber optic illumination channel.

26. The endoscope ofclaim 25 wherein the outer tube is a plastic material.

27. The endoscope ofclaim 25 wherein the tube comprises a metal.

28. The endoscope ofclaim 1 wherein the endoscope probe has a length to diameter ratio between 40:1 and 60:1.

29. The endoscope ofclaim 1 further comprising a computer connected to the imaging device.

30. The endoscope ofclaim 29 further comprising an image processing sequence.

31. The endoscope ofclaim 30 wherein the image processing sequence subtracts a stored light distribution pattern from a video image.

32. The endoscope ofclaim 31 wherein the stored light distribution pattern corresponds with a light reflection pattern for the endoscope.

33. The endoscope ofclaim 1 wherein the concentric illumination channel has a thickness of 10 microns.

34. The endoscope ofclaim 1 wherein the concentric illumination channel has a thickness of 30 microns.

35. A miniature endoscope for orthopedic imaging comprising:

a probe for orthopedic diagnostic imaging, the probe including a fiber optic imaging channel having a diameter in a range of 0.6 mm to 1.6 mm and the probe having a diameter less than 2 mm and a mounting hub;

a tube surrounding the imaging channel;

a fiber optic illumination channel within the probe that is concentric about the tube and the imaging channel and a light source that is optically coupled to the fiber optic illumination channel with the mounting hub attached to the handle, the illumination channel having a thickness in a range of 0.1 mm to 0.2 mm;

an outer tube around the fiber optic illumination channel;

a handle removably attached to the probe with a connector;

a cannula that receives a distal end of the probe such that the distal end of the probe slides within the cannula, the cannula having a locking mechanism at a proximal end that attaches to the probe;

a sterile barrier attached to the mounting hub that can be extended over the handle;

a first lens and a second lens that are optically coupled to a distal end of the imaging channel;

an optical relay mounted in the handle and optically coupled to a proximal end of the imaging channel; and

an imaging device mounted in the handle and optically coupled to a proximal end of the optical relay.

36. The miniature endoscope ofclaim 35 wherein the imaging device comprises a charge coupled device.

37. The miniature endoscope ofclaim 35 wherein the imaging channel comprises a transparent material having a refractive index of at least 1.6.

38. The miniature endoscope ofclaim 37 wherein the imaging light channel comprises a glass rod.

39. The miniature endoscope ofclaim 38 wherein the glass rod comprises an F2 or an F7 glass.

40. The miniature endoscope ofclaim 35 further comprising a light absorbing layer around the imaging channel.

41. The miniature endoscope ofclaim 35 wherein the illumination channel is coupled to the light source with a fiber optic connector.

42. The miniature endoscope ofclaim 35 wherein the endoscope has a display connected to the imaging device for arthroscopic examination.

Images